The long term goal of our research is to develop a deep understanding of the genetic factors underlying atherosclerosis, using mice genetically altered by targeting. The upcoming grant period will take advantage of the predictable development of atherosclerosis in our apolipoprotein E-deficient mice to explore how the atherogenic process is affected by mutations in genes other than those directly involved in lipid metabolism. The genes chosen for study in our three specific aims are each individually important for maintaining vascular health and eanh is a likely candidates for altering the vascular response to elevated levels of plasma lipoproteins. In addition, changes in these genes are likely to make current mouse models of atherosclerosis closer to the human condition. Specific aim 1: We will generate a genetic absence of ascorbic acid (vitamin C) synthesis in mice, by disrupting the mouse L-gulono-gamma- lactone oxidase gene, which humans lost during the evolution. We will combine this with a genetic lack of apoE to test the importance of this dietary antioxidant in the prevention of atherosclerosis and in stabilizing atherosclerotic plaques. Specific aim 2: We will test the importance of monocyte recruitment for early lesion development by generating apoE null mice carrying 0, 1, 2, 3, or 4 copies of the chemokine receptor CCR2 gene, coding for the primary receptor for the chemokine MCP-1 (monocyte chemoattractant protein 1). Specific aim 3: We will test the hypothesis that mutations causing elevation in the blood pressures of animals will influence the development, distribution, and the stability of atherosclerotic plaques by combining apoE deficiency with mutations in genes coding for angiotensinogen, endothelial nitric oxide synthase or natriuretic peptide receptor A.